# 1.9 Physical quantities and units  (Page 5/18)

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Click [link] for a more complete list of conversion factors.

Approximate values of length, mass, and time
Lengths in meters Masses in kilograms (more precise values in parentheses) Times in seconds (more precise values in parentheses)
${\text{10}}^{-\text{18}}$ Present experimental limit to smallest observable detail ${\text{10}}^{-\text{30}}$ Mass of an electron ${\text{10}}^{-\text{23}}$ Time for light to cross a proton
${\text{10}}^{-\text{15}}$ Diameter of a proton ${\text{10}}^{-\text{27}}$ Mass of a hydrogen atom ${\text{10}}^{-\text{22}}$ Mean life of an extremely unstable nucleus
${\text{10}}^{-\text{14}}$ Diameter of a uranium nucleus ${\text{10}}^{-\text{15}}$ Mass of a bacterium ${\text{10}}^{-\text{15}}$ Time for one oscillation of visible light
${\text{10}}^{-\text{10}}$ Diameter of a hydrogen atom ${\text{10}}^{-5}$ Mass of a mosquito ${\text{10}}^{-\text{13}}$ Time for one vibration of an atom in a solid
${\text{10}}^{-8}$ Thickness of membranes in cells of living organisms ${\text{10}}^{-2}$ Mass of a hummingbird ${\text{10}}^{-8}$ Time for one oscillation of an FM radio wave
${\text{10}}^{-6}$ Wavelength of visible light $\text{1}$ Mass of a liter of water (about a quart) ${\text{10}}^{-3}$ Duration of a nerve impulse
${\text{10}}^{-3}$ Size of a grain of sand ${\text{10}}^{2}$ Mass of a person $\text{1}$ Time for one heartbeat
$\text{1}$ Height of a 4-year-old child ${\text{10}}^{3}$ Mass of a car ${\text{10}}^{5}$ One day $\left(8\text{.}\text{64}×{\text{10}}^{4}\phantom{\rule{0.25em}{0ex}}\text{s}\right)$
${\text{10}}^{2}$ Length of a football field ${\text{10}}^{8}$ Mass of a large ship ${\text{10}}^{7}$ One year (y) $\left(3\text{.}\text{16}×{\text{10}}^{7}\phantom{\rule{0.25em}{0ex}}\text{s}\right)$
${\text{10}}^{4}$ Greatest ocean depth ${\text{10}}^{\text{12}}$ Mass of a large iceberg ${\text{10}}^{9}$ About half the life expectancy of a human
${\text{10}}^{7}$ Diameter of the Earth ${\text{10}}^{\text{15}}$ Mass of the nucleus of a comet ${\text{10}}^{\text{11}}$ Recorded history
${\text{10}}^{\text{11}}$ Distance from the Earth to the Sun ${\text{10}}^{\text{23}}$ Mass of the Moon ${\text{10}}^{\text{17}}$ Age of the Earth
${\text{10}}^{\text{16}}$ Distance traveled by light in 1 year (a light year) ${\text{10}}^{\text{25}}$ Mass of the Earth ${\text{10}}^{\text{18}}$ Age of the universe
${\text{10}}^{\text{21}}$ Diameter of the Milky Way galaxy ${\text{10}}^{\text{30}}$ Mass of the Sun
${\text{10}}^{\text{22}}$ Distance from the Earth to the nearest large galaxy (Andromeda) ${\text{10}}^{\text{42}}$ Mass of the Milky Way galaxy (current upper limit)
${\text{10}}^{\text{26}}$ Distance from the Earth to the edges of the known universe ${\text{10}}^{\text{53}}$ Mass of the known universe (current upper limit)

## Unit conversions: a short drive home

Suppose that you drive the 10.0 km from your university to home in 20.0 min. Calculate your average speed (a) in kilometers per hour (km/h) and (b) in meters per second (m/s). (Note: Average speed is distance traveled divided by time of travel.)

Strategy

First we calculate the average speed using the given units. Then we can get the average speed into the desired units by picking the correct conversion factor and multiplying by it. The correct conversion factor is the one that cancels the unwanted unit and leaves the desired unit in its place.

Solution for (a)

(1) Calculate average speed. Average speed is distance traveled divided by time of travel. (Take this definition as a given for now—average speed and other motion concepts will be covered in a later module.) In equation form,

$\text{average speed =}\frac{\text{distance}}{\text{time}}\text{.}$

(2) Substitute the given values for distance and time.

(3) Convert km/min to km/h: multiply by the conversion factor that will cancel minutes and leave hours. That conversion factor is $\text{60 min/hr}$ . Thus,

Discussion for (a)

who was the first nanotechnologist
k
Veysel
technologist's thinker father is Richard Feynman but the literature first user scientist Nario Tagunichi.
Veysel
Norio Taniguchi
puvananathan
Interesting
Andr
I need help
Richard
@Richard Is that Richard Feynman
Vince
anyone have book of Abdel Salam Hamdy Makhlouf book in pdf Fundamentals of Nanoparticles: Classifications, Synthesis
what happen with The nano material on The deep space.?
It could change the whole space science.
puvananathan
the characteristics of nano materials can be studied by solving which equation?
sibaram
synthesis of nano materials by chemical reaction taking place in aqueous solvents under high temperature and pressure is call?
sibaram
hydrothermal synthesis
ISHFAQ
how can chip be made from sand
is this allso about nanoscale material
Almas
are nano particles real
yeah
Joseph
Hello, if I study Physics teacher in bachelor, can I study Nanotechnology in master?
no can't
Lohitha
where is the latest information on a no technology how can I find it
William
currently
William
where we get a research paper on Nano chemistry....?
nanopartical of organic/inorganic / physical chemistry , pdf / thesis / review
Ali
what are the products of Nano chemistry?
There are lots of products of nano chemistry... Like nano coatings.....carbon fiber.. And lots of others..
learn
Even nanotechnology is pretty much all about chemistry... Its the chemistry on quantum or atomic level
learn
da
no nanotechnology is also a part of physics and maths it requires angle formulas and some pressure regarding concepts
Bhagvanji
hey
Giriraj
Preparation and Applications of Nanomaterial for Drug Delivery
revolt
da
Application of nanotechnology in medicine
has a lot of application modern world
Kamaluddeen
yes
narayan
what is variations in raman spectra for nanomaterials
ya I also want to know the raman spectra
Bhagvanji
I only see partial conversation and what's the question here!
what about nanotechnology for water purification
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
Damian
yes that's correct
Professor
I think
Professor
Nasa has use it in the 60's, copper as water purification in the moon travel.
Alexandre
nanocopper obvius
Alexandre
what is the stm
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
Rafiq
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
Damian
STM - Scanning Tunneling Microscope.
puvananathan
how did you get the value of 2000N.What calculations are needed to arrive at it
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